package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

//使用这个类封装针对user类的增删改查操作
public class UserDao {
    //1、根据userId查询用户 (根据博客来查询作者信息）
    public User getUserById(int userId) {
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            connection = DBUtil.getConnection();
            String sql = "select * from user where userId=?";
            statement = connection.prepareStatement(sql);
            statement.setInt(1,userId);
            resultSet = statement.executeQuery();
            if(resultSet.next()) {
                User user = new User();
                user.setUserId(resultSet.getInt("userId"));
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
                return user;
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            DBUtil.close(connection, statement, resultSet);
        }
        return null;
    }

    //2、根据username查询用户（实现登录功能）
    public User getUserByName(String username) {
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            connection = DBUtil.getConnection();
            String sql = "select * from user where username = ?";
            statement = connection.prepareStatement(sql);
            statement.setString(1,username);
            resultSet = statement.executeQuery();
            if(resultSet.next()) {
                User user = new User();
                user.setUserId(resultSet.getInt("userId"));
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
                return user;
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            DBUtil.close(connection, statement, resultSet);
        }
        return null;
    }
}
